Man Portable Air Defense Systems (MANPADS), such as shoulder-launched missiles, have been proliferated throughout the world, creating a potential danger not only to military aircraft, but also to commercial aircraft. Countermeasures against MANPADS and similar threats to aircraft safety have been developed primarily for military aircraft. As a result, concerns regarding the safety of commercial transport aircraft—and in particular, commercial aircraft survivability against the threat of MANPADS—have increased sharply during recent years.
A majority of MANPADS implement infrared (IR) band seekers. IR seekers track a target aircraft in response to individual thermal sources, such as engine hot parts, plumes, lighting elements, heated aircraft surfaces and reflections. Past attempts to achieve aircraft survivability in response to MANPADS have commonly focused on susceptibility reduction, or “hit avoidance,” features. Infrared countermeasures (IRCM) aimed at reducing the likelihood of aircraft impact after launch of infrared-seeking threats have included pyrotechnic or pyrophoric devices, such as flares, expendables, other incendiary devices or infrared chaff; infrared lamp countermeasures; and either advanced-threat infrared countermeasures (ATIRCM) or directed infrared countermeasures (DIRCM), which can use directed, high-powered lamps or lasers to disrupt MANPADS tracking capability.
Generally, existing IRCM systems require knowledge of a missile launch to be effective. For some systems, both launch warning and missile approach direction knowledge are required for the system to be effective. Flares or other expendables can be dispensed in reaction to a launch warning or in anticipation of a launch, but the duration of protection is limited by the payload of expendables. Although launch warning is not required for an omni-directional IR lamp countermeasure, the IR lamp systems are not highly effective against some MANPADS threats.
A classic example of an operational vulnerability reduction system is a sacrificial engine-nozzle extension implemented on some Israeli A4 aircraft. Infrared-seeking missiles attracted to this hot-spot location destroyed only the sacrificial extension. Flight-critical engine components were protected. Some limitations of the nozzle extension concept include the considerable weight of the sacrificial extension and the prohibitively high cost of retrofit on most aircraft types. In addition, the sacrificial engine nozzle extension used on Israeli A-4 aircraft is not well-suited for many commercial aircraft which have an under wing installation of engines on the main wing, since such an extension would need to protrude a considerable distance aft of the engine in order to be clear of the aircraft fuselage and empennage.
As an alternative to—or in addition to—hit avoidance features, countermeasures can include “hit acceptance” features. For example, an infrared lamp can be installed on a sacrificial support structure to protect the targeted aircraft's most critical components. Approaching missiles are coaxed away from the aircraft's most critical zones, increasing aircraft survivability to MANPADS missile hits.
However, technologies that have been developed and implemented for military or other specialized purposes generally are incompatible with commercial aircraft operations. Moreover, even to the extent that existing technologies may be compatible with commercial aircraft operations, development of commercial implementations of the technologies would require an extended period of time.
Accordingly, it is desirable to provide a countermeasure for infrared-seeking threats that is relatively inexpensive, can be developed and implemented in a relatively short period of time on a significant portion of the commercial aircraft fleet, and can significantly increase aircraft survivability without creating new vulnerabilities.